L-4 Cell Organelles

7/31/2019 L-4 Cell Organelles

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Levels of Organization

atom - smallest unit of an element molecule - unit of 2 or more atoms organelle - structures with specific jobs inside a cell cell - smallest living unit tissue - group of same cells functioning together organ - structural unit of different tissues

organ system - two or more organs interacting organism - group of organ systems working together population - group of individuals of same kind community - all populations living in an area ecosystem - community and its physical environment

biosphere - region where life exists

all living organisms display levels of complexity


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(The fundamentalunit of life)

(A membrane bound structure

within a complex cell)

( A small groupof joined atoms)

(The smallest chemicalunit of a type of puresubstance or element)

(A collection ofspecialized cells)


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(where life is possible)

(living andnon living

environment)

(All organisms in agiven place & time)

(A group ofthe sametypeof organism

living in thesame place

and time)

(A structure consisting of

tissues organized to carry outspecific functions)

(Organs connected physically orChemically that function together)

(A living individual)


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THE CELLCELL WALL

non-living structure rigid

made primarily of a substance called cellulose

selectively permeable

found only in plant cells functions are - protect contents of cell (injury)

- regulate flow of materials in andout of cell


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CELL MEMBRANE

also called "plasma membrane"

flexible

structurally a phospholipid bi-layer head faces out and is "hydrophilic"

tail faces in and is "hydrophobic"

common to all living cells

outermost membrane in all cells except plants (cell wall is)

function -to regulate materials moving in and out of cell


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FLAGELLA and CILIA

flagellum is a long whip-like structure

contractile proteins allow a corkscrew action functions in propulsion (ex. human sperm cell)

cilium is a short hair-like structure

contractile proteins move in a co-ordinated wave motion

is used for locomotion and moving materials


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PROTOPLASM

a "gel" in which all other organelles are suspended

composition varies with different types of cells

contains proteins, fats, carbohydrates, vitamins, minerals,water, etc.

it can be sub-divided into two types (by location)

- nucleoplasm (in nucleus only)

- cytoplasm (in the rest of the cell)


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NUCLEUS usually the largest organelle is sac-like or spherical in shape usually only one nucleus per cell

found - the central portion of the animal cell- off to one side in plant cells

contains the genetic material functions - store house of genetic material

- co-ordination centre for all cell activities

NUCLEOLUS found in the nucleus oval or spherical bodies no outer membrane made up primarily of protein and RNA usually 1 to 4 per nucleus function -the synthesis of ribosomes


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NUCLEAR MEMBRANE

a double membrane surrounding the nucleus

flexible

selectively-permeable

regulates materials going in and out of nucleus


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CHROMATIN

found in the nucleus

long thin threads

are acidic

are given different names according to their shape

- long thin threads - chromatin

- short thick threads - chromosome

function - carrier of genetic information


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RIBOSOMES

smallest natural structure in the cell

made up of two spheres

- large sub-unit (Ls) found on top - small sub-unit (Ss) found on bottom

made up of RNA

usually found attached to the endoplasmic reticulum

when found free floating in cytoplasm called "endosomes" function -site of protein synthesis


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ENDOPLASMIC RETICULUM

hollow, tubular structure

meanders through the cytoplasm

connects the cell membrane to the nuclear membrane

exists in two forms- smooth E.R. - no ribosomes attached

- rough E.R. - ribosomes attached

functions - site of internal transportation

- site for chemical reactions

- makes fats and carbohydrates


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GOLGI APPARATUS

usually a system of double layered flattened sacs

lie one on top of the other

found close to the nucleus

functions -produces lysosomes

-makes membranes

-storage for lipids


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LYSOSOMES

single membrane

varies in shape and size (pleomorphic) formed in the region of the golgi apparatus

numbers per cell varies

have three important functions

- site of intra-cellular digestion

- destruction of harmful chemicals

- "autolysis" of damaged cells


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MITOCHONDRION rod shaped structure double walled

-outer wall - smooth and continuous -inner wall - highly convoluted

- finger-like projections called "cristae"- "elementary particles" on top of crista- "lamella" is space between cristae

number per cell varies greatly site of "aerobic respiration


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CENTRIOLES tubular structure found in two arrangements

-single tubule - centriole-double tubule - centrosome

- 2 centrioles perpendicular to each other found only in animal cells are close to the nucleus two major functions:

- with the production of cilia and flagella- "basal body" if embedded in cell membrane- assists in cell division


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VACUOLES

spherical structure

found through out the cytoplasm animal cells - many small ones

plant cells - few large ones

generally they hold materials to be eliminated from the cell


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GRANULAR INCLUSIONS smallest structure in the cell cell fragments found in cytoplasm (only in animal cells)

function is unknown

MICROFILAMENTS

pipe like structures found in the cytoplasm

provide shape andmovement for cell

MICROTUBULES

tiny tube like fibres composed of protein found in cilia and flagella transport materials

throughout the cytoplasm


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Endocytosis

the process by which the cell membrane wraps around aparticle and pinches off a vesicle inside the cell

Exocytosis

The process by which particles are released from a cell byfusing a particle filled vesicle off a vesicle with the cellmembrane


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Generalized Eukaryotic Cell

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L-4 Cell Organelles